In Xerography or an electrostatic marking system and process, a uniform electrostatic charge is placed upon a photoreceptor surface. The charged surface is then exposed to a light image of an original to selectively dissipate the charge to form a latent electrostatic image of the original. The latent image is developed by depositing finely divided and charged particles of toner upon the photoreceptor surface. The charged toner being electrostatically attached to the latent electrostatic image areas to create a visible replica of the original. The developed image is then usually transferred from the photoreceptor surface to a final support material, such as paper, and the toner image is fixed thereto to form a permanent record corresponding to the original.
In Xerographic copiers or printers, a photoreceptor surface is arranged to move in an endless path through the various processing stations of the xerographic process. Since the photoreceptor surface is reusable, the toner image is then transferred to a final support material, such as paper, and the surface of the photoreceptor is prepared to be used once again for the reproduction of a copy of an original. In this endless path, several Xerographic related processing stations are traversed by the photoconductive belt.
Each of these processing stations generally include a source of power usually a single motor to provide the necessary processing at that station. The term “power” as used throughout the disclosure and claims includes rotational torque. For example: a motor is needed to turn or rotate the fuser and pressure rollers in the fusing station; or similarly a motor is needed to move the photoconductor or transport the paper, etc. In addition, marking systems include stations that supply paper and others that perform functions on multiple sheets of paper or sets. These functions include stapling, binding, hole punching and many other specialized “finishing” operations. In these examples, a motor is often used to rotate a mechanism to a position needed for a variable function of that station. For example: a motor might be employed to move staplers in accordance with inputs provided by a customer, or a motor might move a mechanism that pushes the set to a new location and must change the amount of push based on the set size. Another type of example found in both paper supplying stations and finishing stations there is often a need to accelerate individual sheets away from those following to increase the time for subsequent operations. Generally, the motors used have one fixed speed ratio between the motor and the load, and the motors must be sized for all speed and load combinations. A fixed gear ratio sometimes can be made more versatile by the use of transmissions and clutches, but these transmissions and clutches generally are a source of unreliability and mechanical failure.
Thus, prior art motors generally are applied with a fixed non-adjustable ratio which is set by the geometry of the drive elements. There are cases where the ability to employ a variable ratio would allow a flexibility not found with fixed ratio systems.
Also, in electrophotographic or electrostatic marking systems, several motors of different sizes and capabilities are needed since the requirements at the various stations differ greatly. Therefore, a very large inventory of different size and types of motors are required to be kept. Many of these inventoried motors don't meet all of the requirements of the intended stations and either need to be modified or concessions on their use need to be considered. Any means to help reduce this very large inventory of motors would be desired both from an expense standpoint and a logistics standpoint.
The customary processing stations in an electrostatic marking system comprise a charging station, an exposure station, a development station, a transfer station, a detack station, a fusing station, a cleaning station, a paper supply station, paper transport stations, and finishing stations. By “customary” as used throughout this disclosure and claims will include the aforementioned stations. Each of these stations have unique needs such as speed of processing, amount of torque and type of control, etc. It is clear to imagine why so many different motors are needed to be inventoried to accommodate all of these various stations' needs.
Therefore, when designing drive trains for xerographic machines, there is often a compromise made between the requirements, such as gear ratio and the capability of the motor. As above noted, since transmissions and clutches are a source of unreliability, other convenient ways to achieve variable gear ratios are desired.